Preheat the oven to 350 degree. Add the cake mix, oil, eggs and water in an electric mixer. Beat on low speed for two minutes.
Remove 1/4 of the batter and place in a separate bowl. You will have two bowls of batter, one that will be two layers of the same color and the other will be one layer of a lighter blue.
Add 1/8 teaspoon (or less) of food coloring to each bowl and mix until you achieve your desired color.
Line the bottom of the round cake pans with parchment paper and spray with oil so the cake will not stick.
Bake the cakes for 20 minutes or until a toothpick comes out clean. If you only have two round cake pans, cook two and then cook the third while the other two cool.
Allow all three cakes to cool completely before stacking. When cooled, place the first layer on a cake stand and frost the top. Then add the second layer and another layer of frosting. Then the third layer and frost.
When the three layers are stacked and frosted, frost the sides of the cake.
Line the bottom and top of the cake with Gushers and then you're done!
